It was the smart glasses Google Glass Explorer Edition supported since the company has stopped Google from the production of these glasses of the future-looking at 2015, but they rarely get updates. Thus, it is not surprising now to see Google decide now fully support these smart glasses in the month of February. The last update of these glasses, which was released just prepare for that step.
You must install this update ultimate manually remove contact Google Glass services background in addition to the ability of the device to use your Google account, so there is no longer a Gmail and Youtube and Google Glass. You can still connect with your smartphone via Bluetooth and will retain some functions such as capturing photos and videos and run applications that are lifted and installed manually on the glasses.
As for the glasses Google Glass Entreprise Edition, it will not be affected by this decision and will continue to Google support.